CyberSecBulletin
CVE-2024-44934NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-44934 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 1e16828020c674b3be85f52685e8b80f9008f50f, 0d8b26e10e680c01522d7cc14abe04c3265a928f, e3145ca904fa8dbfd1a5bf0187905bc117b0efce as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.22% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 1e16828020c674b3be85f52685e8b80f9008f50f or 0d8b26e10e680c01522d7cc14abe04c3265a928f or e3145ca904fa8dbfd1a5bf0187905bc117b0efce or b2f794b168cf560682ff976b255aa6d29d14a658, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.165 or 6.1.105 or 6.6.46 or 6.10.5, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxe12cec65b5546f19217e26aafb8add6e2fadca18 up to, but not including, 1e16828020c674b3be85f52685e8b80f9008f50f; e12cec65b5546f19217e26aafb8add6e2fadca18 up to, but not including, 0d8b26e10e680c01522d7cc14abe04c3265a928f; e12cec65b5546f19217e26aafb8add6e2fadca18 up to, but not including, e3145ca904fa8dbfd1a5bf0187905bc117b0efce; e12cec65b5546f19217e26aafb8add6e2fadca18 up to, but not including, b2f794b168cf560682ff976b255aa6d29d14a658; e12cec65b5546f19217e26aafb8add6e2fadca18 up to, but not including, 92c4ee25208d0f35dafc3213cdf355fbe449e078; 5.101e16828020c674b3be85f52685e8b80f9008f50f, 0d8b26e10e680c01522d7cc14abe04c3265a928f, e3145ca904fa8dbfd1a5bf0187905bc117b0efce, b2f794b168cf560682ff976b255aa6d29d14a658, 92c4ee25208d0f35dafc3213cdf355fbe449e078
LinuxLinux Kernel5.10 up to, but not including, 5.15.165; 5.16 up to, but not including, 6.1.105; 6.2 up to, but not including, 6.6.46; 6.7 up to, but not including, 6.10.5; 6.115.15.165, 6.1.105, 6.6.46, 6.10.5

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: mcast: wait for previous gc cycles when removing port syzbot hit a use-after-free[1] which is caused because the bridge doesn't make sure that all previous garbage has been collected when removing a port. What happens is: CPU 1 CPU 2 start gc cycle remove port acquire gc lock first wait for lock call br_multicasg_gc() directly acquire lock now but free port the port can be freed while grp timers still running Make sure all previous gc cycles have finished by using flush_work before freeing the port. [1] BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699 CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc3/0x620 mm/kasan/report.c:488 kasan_report+0xd9/0x110 mm/kasan/report.c:601 br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861 call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792 expire_timers kernel/time/timer.c:1843 [inline] __run_timers+0x74b/0xaf0 kernel/time/timer.c:2417 __run_timer_base kernel/time/timer.c:2428 [inline] __run_timer_base kernel/time/timer.c:2421 [inline] run_timer_base+0x111/0x190 kernel/time/timer.c:2437

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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